Adding day 18 p1 and 19 p1 + creating folder 2018

2018/day5/part1.scala

@@ -0,0 +1,14 @@
+import scala.io.StdIn._
+
+val ASCII_MIN_MAJ_INTERVAL = 32 // 'a' - 'A'
+
+val res = readLine
+  .foldLeft(""){
+    case (acc, chr) => chr match {
+      case _ if acc.isEmpty => chr.toString
+      case _ if (acc.last - chr).abs == ASCII_MIN_MAJ_INTERVAL => acc.dropRight(1)
+      case _ => acc + chr
+    }
+  }
+
+println(res.size)

2018/day5/part2.scala

@@ -0,0 +1,21 @@
+import scala.io.StdIn._
+
+val ASCII_MIN_MAJ_INTERVAL = 32
+
+def reactingPolymer(poly: String, unit: Char): String = unit match {
+  case _ if poly.isEmpty => unit.toString
+  case _ if (poly.last - unit).abs == ASCII_MIN_MAJ_INTERVAL => poly.dropRight(1)
+  case _ => poly + unit
+}
+
+val polymer_v1 = readLine.foldLeft("")(reactingPolymer)
+val unitTypes = polymer_v1.toLowerCase.toSet
+
+unitTypes
+  .map(u => (u, polymer_v1.filter(c => c != u && c + ASCII_MIN_MAJ_INTERVAL != u)))
+  .map { case (u, poly) => (u, poly.foldLeft("")(reactingPolymer).size) }
+  .toList
+  .sortBy(_._2)
+  .map { case (u, size) => s"Could reach size $size by removing $u" }
+  .take(1)
+  .foreach(println)